Orgasms while......

Ok this is embarrassing so I'll post anonymous. Has anyone experienced waking up to yourself having a orgasm while pregnant? I had it happen for the first time about a month ago. And I thought it was a dream, but just a few days ago it happened again..... a friend of mine told me it happened to her a long time ago but I didn't believe it and now I do...... I looked it up on the internet and there are people who say it happens. Just curious on how common it is..